Re: Venting lavatory sinks
Posted by Deb on March 21, 2004 at 16:10:37:
In response to Re: Venting lavatory sinks
: : : I am remodelling my bathroom and the position of the vanity basins is to be moved. I thought I could just drain the new basins into the same drain that the shower and bath go into but looking around your site it seems that this is more complex. I had never heard of venting until I checked out your site! Can someone advise me on how I should do this?

: : : The bathroom is on the top floor. At present the bath tub drain runs about 10' sloped horizontally, the shower drain runs about 5' - they both are 1 1/2" ABS pipes which join in a Y into a 2" drain which has a 2" vent pipe to the roof which eventually T's into a 3" pipe out through the roof (many other 2" and 3" pipes T into this as well). The existing vanity basins have their own vent pipe but I can't get to this because of the joists.

: : : On the same wall that the new basins are to be installed there is another 3" vent pipe but I am not sure what it is venting as there is no bathroom beneath this.

: : : So my questions:
: : : 1. Is it ok to run the new vanities into the same drain as the bath and shower?
: : : 2. Do I need a new vent?
: : : 3. Can I T into another vent pipe or do I have to run a new pipe to the attic and T into the 3"? Cutting the holes for a new pipe will be very difficult so I would like to avoid this.
: : : 4. If I have to run a new vent should it be 2"?

: : : Hope you can help,
: : : Phil

: : Reply:
: : Does the existing bathtub and shower drain traps each have their own individual vent lines connected next to their traps?

: : 1. Is it ok to run the new vanities into the same drain as the bath and shower?
: : >The existing 2" should handle it with no trouble, tie into a horizontal drain with a wye.
: : 2. Do I need a new vent?
: : >Yes, all fixtures need to be vented, if you're installing double lavs on the same counter, you can connect them with one trap and one vent, (within 30", C to C)
: : 3. Can I T into another vent pipe or do I have to run a new pipe to the attic and T into the 3"? Cutting the holes for a new pipe will be very difficult so I would like to avoid this.
: : >Either way, you probably will not overload an existing vent line.
: : 4. If I have to run a new vent should it be 2"?
: : >The double lavs require an 1-1/2" vent.

: : Good Luck. e-plumber

: Thanks. Both tub and shower have p-traps which connect to 1-1/2" drain pipes, these join at a Y joint (10' from tub p-trap, 5' from shower p-trap). After the Y the drain becomes 2" and about 1' later a T takes the drain vertically down and the vent up to the attic space where it Ts into a 3" pipe that goes through the roof. I hope this is ok - I haven't touched this and as far as I know there has been no problems i.e. everything drains efficiently (although when first running the shower it sounds like the bath is draining).

: From your answers it looks like I can join the lav drain to the tub/shower drain and tie into the other vent - this is good news and looks very easy to do.

: Thanks again,
: Phil

Just so you are aware. The tub and shower are not vented, according to UPC code. The shower drain and p-trap are undersized. A vent needs to be taken off each, prior to them tying together. The vent is way too far away to be venting 1-1/2" traps. If you tie the lav in, it sounds like you will be tying into a trap arm, not a drain line--a no-no. Where I live, this is not even close to code. Quoting UPC code, you may be under another.
Deb
The Pipewench


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